With the increasing public concern for safety, there is a clear need to provide safe materials for commercial and residential use. One particular area of need is to provide flame resistant or flame retardant polymer products. As a result of this demand, many products are required to meet specified flame retardant criteria by both local and federal governments. A well known test for the flammability of polymer materials, such as polycarbonate compositions, is set forth in Underwriter's Laboratories, Bulletin UL-94, Third Edition (1980). This bulletin sets forth tests by which polymer materials are rated for self-extinguishing characteristics.
Many flame retardant additives are known which are employed by mixing with a base polymer to render such polymer self-extinguishing or flame retardant. Such flame retardant additives have been known to be employed in amounts up to about 20 weight percent in order to be effective in extinguishing burning polymer materials. However, it has been found that such high amounts of flame retardant additives can have a degrading effect upon the base polymer, resulting in the loss of valuable physical properties of the base polymer. For example, thermal stability, color and corrosion problems are often associated with prior flame retardant additives. In addition, gases generated during polymer burning may be hazardous if, for example, the flame retardant additive contains halogen. The loss of valuable physical properties when prior flame retardant additives are combined with a base polymer is particularly accute when the base polymer is a polycarbonate resin.